The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Environmentally-friendly techniques of vehicles are very important, and the survival of the future motor industry is dependent thereon. Vehicle makers are focusing on development of environmentally-friendly vehicles so as to meet environmental and fuel consumption regulations.
Some examples of applications of such future vehicle techniques are a hybrid electric vehicle (HEV) and a dual clutch transmission (DCT).
The DCT includes two clutches and a gear train applied to a manual transmission. The DCT selectively transmits torque output from a torque source (e.g., an engine or driving motor) to two input shafts by using two clutches, changes a speed by using the gear train, and outputs the changed torque.
Such a DCT is used to provide a compact transmission having five or more forward speed stages. Since two clutches and synchronizers are controlled by a controller, a manual shift maneuver is unnecessary for controlling the DCT. Therefore, the DCT is one type of automated manual transmission (AMT).
The hybrid electric vehicle uses an internal combustion engine and a battery power source together. In other words, the hybrid electric vehicle efficiently combines and uses torque of the internal combustion engine and torque of a driving motor. Since the hybrid electric vehicle uses both mechanical energy of the engine and electrical energy of the battery, uses desired operation regions of the engine and the motor, and recovers energy upon braking, fuel efficiency may be improved and energy may be efficiently used.
The hybrid electric vehicle provides driving in an electric vehicle (EV) mode in which only torque of the driving motor is used, a hybrid electric vehicle (HEV) mode in which torque of the engine is used as main torque and torque of the driving motor is used as auxiliary torque, and a regenerative braking mode in which braking and inertial energy are recovered through electrical power generation of the driving motor during braking of the vehicle or during deceleration of the vehicle by inertia to be charged in the battery.
In the method for controlling the hybrid electric vehicle according to the related art, when the EV mode is switched to the HEV mode (i.e., when the engine starts), after a speed of the engine is synchronized to a speed of the driving motor, drivability may be provided to inhibit or prevent engagement shock from occurring while torque is delivered between the engine and the motor which are different torque sources by engaging an engine clutch.
However, in a case where a position value of an accelerator pedal is very high or torque of the driving motor is limited, a time until the speed of the motor reaches the speed of the engine (i.e., a time in which torque of the engine is not used as driving torque of the hybrid electric vehicle) is increased, thereby deteriorating acceleration performance of the hybrid electric vehicle.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.